Quantum Computing Made Simple(r), IBM Research Closer To First 'Practical' Machine

Aliens landing from Mars might have trouble working out what IBM is. The firm’s ‘About Us’ pages are fond of talking about the ‘Smarter Planet’ and its IBM Research home page kicks off with ‘The World Is Our Laboratory’ no less. Maybe it’s all a ruse to convince the Martians that IBM is in fact in control of Earth. In fact, IBM is an IT company with a heritage in both mainframes and desktop computing manufacturing with a new outlook on services and cloud computing.

Of course IBM can’t help but express itself in these terms given the size of its internal research capability, so let’s be sensible for a moment. The firm’s scientists have unveiled two critical advances towards the realization of what might be the first 'practical' quantum computer.

What is quantum computing?

Our plain old digital computers rely on data that is encoded into the binary system of 0s and 1s. In binary, the state of a bit is either 0 or 1 and that’s all its ‘position’ can be. The next age of quantum computers use qubits (or quantum bits) whose ‘superposition’ can be both 0 and 1 simultaneously. This fundamental of quantum computing means that things can be different things depending on the context in which they are viewed. Without going too deep into non-deterministic probabilistic computational analysis, this means that quantum computers can offer us more power, when they arrive.

But quantum states are inherently fragile, so kid gloves are needed here. IBM says that for the first time, it has showed the ability to detect and measure both kinds of quantum errors simultaneously. It also says it has demonstrated a new square quantum bit circuit design that is the only physical architecture that could successfully scale to larger dimensions.

According to IBM, “With Moore’s Law running out of steam, quantum computing will be among the inventions that could usher in a new era of innovation across industries. Quantum computers promise to open up new capabilities in the fields of optimization and simulation simply not possible using today’s computers. If a quantum computer could be built with just 50 quantum bits (qubits), no combination of today’s TOP500 supercomputers could successfully outperform it.”

How could quantum computing help us humans?

In physics and chemistry, quantum computing could allow scientists to design new materials and drug compounds without expensive trial and error experiments in the lab, dramatically speeding up the rate and pace of innovation across many industries.

For a world consumed by big bata, quantum computers could quickly sort and curate ever-larger databases as well as massive stores of diverse, unstructured data. This could transform how people make decisions and how researchers across industries make critical discoveries.

One of the great challenges for scientists seeking to harness the power of quantum computing is controlling or removing so-called ‘quantum decoherence’ – the creation of errors in calculations caused by interference from factors such as heat, electromagnetic radiation and material defects. The errors are especially acute in quantum machines, since quantum information is so fragile.

“Up until now, researchers have been able to detect bit-flip or phase-flip quantum errors, but never the two together. Previous work in this area, using linear arrangements, only looked at bit-flip errors offering incomplete information on the quantum state of a system and making them inadequate for a quantum computer,”said Jay Gambetta, a manager in the IBM Quantum Computing Group. “Our four qubit results take us past this hurdle by detecting both types of quantum errors and can be scalable to larger systems, as the qubits are arranged in a square lattice as opposed to a linear array.”

The work at IBM was funded in part by the IARPA (Intelligence Advanced Research Projects Activity) multi-qubit-coherent-operations program.

Quantum information is very fragile because all existing qubit technologies lose their information when interacting with matter and electromagnetic radiation. Theorists have found ways to preserve the information much longer by spreading information across many physical qubits. “Surface code” is the technical name for a specific error correction scheme which spreads quantum information across many qubits.

It allows for only nearest neighbor interactions to encode one logical qubit, making it sufficiently stable to perform error-free operations. The IBM Research team used a variety of techniques to measure the states of two independent syndrome (measurement) qubits, which each reveals one aspect of the quantum information stored on two other qubits (called code, or data qubits). Specifically, one syndrome qubit revealed whether a bit-flip error occurred to either of the code qubits, while the other syndrome qubit revealed whether a phase-flip error occurred.

IBM has been working with quantum information processing for more than 30 since the very first workshop in this field on the Physics of Information in 1981.